Lectins comprise a large superfamily of carbohydrate-binding proteins, which have evolutionary conserved structure and function among many species. Recent evidence suggests that soluble lectins not only bind and opsonize bacteria, but may also function on the cell surface as receptors that affect multiple immune responses. Therefore, it is evident that a renewed investigation of the role of lectins in the immune response is needed. Caenorhabditis elegans is an ideal model system for these studies, with its fully sequenced genome, short lifespan and genetic tractability. Preliminary experiments indicate that out of 181 putative lectin domain-containing genes tested, there are 34 candidate lectin genes that reproducibly play a critical role in the defense response of C. elegans to Salmonella enterica. Our goals for this proposal are: 1. To further characterize these candidate genes in the C. elegans defense response to other pathogens and to the C. elegans lifespan, 2. To elucidate the function of these lectins and, 3. To delineate the pathways through which these lectins function. These studies will further our understanding of how lectins function in the innate immune response of C. elegans and may provide insight into the function of lectins in mammals.